Ultrasonic apparatus have been used to perform cutting operations on a workpiece. In an ultrasonic cutting apparatus, a cutting tool is connected to an ultrasonic vibrating device and vibrated to cut the workpiece. U.S. Pat. No. 5,228,372 relates to an ultrasonic cutting device including an ultrasonic vibrating device and an elongated cutting blade. U.S. Pat. No. 3,852,144 relates to an ultrasonic seaming and cutting apparatus accommodating different workpiece thickness. U.S. Pat. No. 4,491,491 relates to an ultrasonic separation apparatus which provides simultaneous cutting and sealing of thermoplastic materials.
The workpiece may be a textile fabric, paper, plastic sheet or the like; the workpiece being a single or multiple layer sheet material having a planar cross-sectional shape. If the workpiece has at least some fibers being thermoplastic components, the ultrasonic apparatus can provide a seam along a salvage of the workpiece. Prior art apparatus have been used for simultaneously cutting and seaming the edges formed by the cut. For a workpiece of textile fabric which releases large quantities of monofilament fibers, such as velvet, such simultaneous cutting and seaming reduces the amount of loose filaments which occur during cutting.
In the manufacture of 35 mm film cartridge, a plush velvet material is disposed at the opening of the film cartridge for use as a light-lock. Cutting the velvet by means other than ultrasonic means, such as by a rotating knife, causes loose fibers to contaminate the work environment, and results in a loss of material from lack of width control. In addition, a product quality problem may result if the loose fibers adhere to the 35 mm film. Further, if an adhesive backing is applied to the velvet, the rotating knife is adversely affected by the adhesive. However, the plush velvet material disposed at the opening of the film cartridge has a non-planar shape, and difficulty is experienced using conventional ultrasonic means when the workpiece is not of a planar shape.
Accordingly, a need continues to exist for an apparatus which ultrasonically cuts a workpiece having a non-planar shape. Further, such an apparatus should not result in loose fibers and a loss of material.